A team of Harvard roboticists has created flying microrobots nicknamed RoboBees that are powered by static electricity. In addition, the unique robots have the ability to perch during flight in order to save energy, just like bats, birds and butterflies.
"Many applications for small drones require them to stay in the air for extended periods," said Moritz Graule, who conducted the research at Harvard University and is first author of the study. "Unfortunately, smaller drones run out of energy quickly. We want to keep them aloft longer without requiring too much additional energy."
In order to achieve this, the team looking to the method of perching used by animals to conserve energy. However, since adhesives, or talons, are not appropriate perching techniques for a tiny robot, the team turned to electrostatic adhesion, the science that is behind a static-charged balloon that sticks to a wall.
Rubbing a balloon onto a wool sweater causes the balloon to become negatively charged, and when this charge comes close to a wall, it forces some of the wall's electrons away, creating a positive charge on the surface of the wall. Subsequently, the attraction between these two charges causes the balloon to stick to it.
"In the case of the balloon, however, the charges dissipate over time, and the balloon will eventually fall down," Graule said. "In our system, a small amount of energy is constantly supplied to maintain the attraction."
The RoboBee utilizes an electrode patch and a foam mount to absorb shock. Its weight is approximately 100 milligrams, similar to that of a real bee. When the electrode patch receives a charge, it is able to stick to almost any surface, and when the power supply is cut off, it detaches.
"One of the biggest advantages of this system is that it doesn't cause destabilizing forces during disengagement, which is crucial for a robot as small and delicate as ours," Graule said.
Since the patch requires around 1,000 times less power to perch than to hover, the RoboBee is able to conserve energy and extend its operational life considerably. As of now, it can only perch under overhangs and on ceilings, but in the future, the team hopes to develop a new mechanical design that allows for perching on any surface.
"There are more challenges to making a robust, robotic landing system but this experimental result demonstrates a very versatile solution to the problem of keeping flying microrobots operating longer without quickly draining power," said Kevin Ma of Harvard University and co-author of the study.
The findings will be published in the May 20 issue of the journal Science.
